Trigeminal branch stimulation for intractable neuropathic pain: technical note

Digital subtraction angiography-guided peripheral nerve stimulation via the foramen rotundum for refractory trigeminal postherpetic neuralgia: a case report and literature review

Postherpetic neuralgia (PHN) is a debilitating complication of varicella-zoster virus infection. This case report presents a novel approach to treating refractory trigeminal maxillary postherpetic neuralgia using digital subtraction angiography (DSA)-guided peripheral nerve stimulation via the foramen rotundum. A 72-year-old female with severe, treatment-resistant pain underwent this intervention. The results demonstrated the disappearance of tactile allodynia, a significant reduction in oral analgesic requirements, and no observed complications or side effects during a 3-year follow-up period. This case highlights the potential effectiveness of DSA-guided peripheral nerve stimulation using a new dorsal root ganglion (DRG) stimulator as an alternative therapy for refractory trigeminal postherpetic neuralgia (TPHN).

Outcome of Surgical Treatments of Chronic Pain Caused by Trigeminal Neuropathy

BACKGROUND

Trigeminal neuropathy represents a subset of several facial pain syndromes that are difficult to diagnose and treat. Although many surgical modalities are available, outcomes remain suboptimal. The aim of this study is to present our experience in management of trigeminal neuropathy with a focus on the effectiveness and long-term efficacy of the different surgical procedures.

METHODS

A single-center retrospective cohort study was conducted from December 2012 until February 2020.

RESULTS

Twenty-eight patients (19 females, 9 males) were included in this study. They had 40 surgical interventions. At last follow-up, 1 patient (33.3%) treated by spinal cord stimulation (SCS) had no pain recurrence and 2 patients (66.6%) had their devices removed because of therapeutic failure. Median time to pain recurrence after SCS was 19.5 months (interquartile range [IQR], 29.79 months). Six patients were treated with peripheral nerve stimulation (PNS). At last follow-up, 2 patients had satisfactory pain relief, whereas half of the patients had no improvement. For the 17 patients treated with computed tomography-guided trigeminal tractotomy/nucleotomy, true failure occurred 7 times in 6 patients. Median time to pain recurrence was 5.6 months (IQR, 6.2). Of the 6 patients treated with caudalis DREZ, 3 (50%) had satisfactory pain relief for >1 year and the median time to pain recurrence was 3.9 months (IQR, 29.53).

CONCLUSIONS

Trigeminal neuropathy is a difficult to treat entity of facial pain syndromes. The long-term efficacy of available interventions does not meet patients' satisfaction. More organized prospective studies with longer follow-up are needed to define the patient population best served by each surgical modality.

Clinical outcomes and complications of peripheral nerve field stimulation in the management of refractory trigeminal pain: a systematic review and meta-analysis

OBJECTIVE

Peripheral nerve field stimulation (PNFS) is a tool in the armamentarium of treatment options for trigeminal pain. The efficacy of this modality in mitigating trigeminal pain remains unclear. The aim of this study was to examine the existing literature on PNFS and elucidate pain score outcomes associated with its use in patients with trigeminal pain.

METHODS

A systematic review and meta-analysis was performed in accordance with the PRISMA framework. The PubMed, Web of Science, and Scopus databases were queried on June 10, 2020. Studies reporting pain outcomes in more than 5 adult patients treated with PNFS for facial pain were included. The primary outcome of the study was the mean difference in the visual analog scale (VAS) score from the last follow-up to baseline, and it was analyzed by an inverse-variance, random-effect model. The risk of bias was assessed using the Newcastle-Ottawa Scale and a funnel plot.

RESULTS

Of the 4597 studies screened for inclusion, 46 relevant full-text articles were assessed for eligibility. Eleven observational cohort studies from the 46 articles were found to be eligible, and reported on a total of 109 patients. In 86% (94/109) of cases, trial stimulation was successful and followed by a permanent system implantation. VAS scores improved by 75% (mean difference 6.32/10 points, 95% CI 5.38-7.27 points) compared to baseline. Seventy-six percent (42/55) of patients became medication free or required lower doses of medications. The complication rate necessitating surgical revision was estimated at 32% per procedure.

CONCLUSIONS

These findings support the belief that PNFS provides effective, long-term pain control for trigeminal pain. Statistical heterogeneity was considerable across all studies. Future work should be aimed at conducting double-blind randomized controlled trials to determine the utility of PNFS for treating various forms of trigeminal pain for which limited therapeutic options exist.

Case Report: Short-Term Spinal Cord Stimulation and Peripheral Nerve Stimulation for the Treatment of Trigeminal Postherpetic Neuralgia in Elderly Patients

Objective: We aimed to report on the use of short-term high cervical spinal cord stimulation (SCS) combined with peripheral nerve stimulation (PNS) to successfully treat trigeminal postherpetic neuralgia (TPHN) affecting the V2 and V3 divisions. We also sought to use a novel PNS approach to the maxillary nerve next to the external opening of the foramen rotundum (FR) to treat TPHN at the V2 division.

Method: Two elderly patients successfully treated with different neuromodulation methods for TPHN are presented in this case series.

Results: The first case referred to an 83-year-old Chinese female patient with V2 and V3 TPHN who experienced a significant pain relief using a combination of short-term high cervical SCS at the C1–C2 level and PNS on the infraorbital nerve (ION). Case 2 was a 68-year-old Chinese male patient with V1 and V2 TPHN that obtained an excellent pain relief after having received short-term PNS on the supraorbital nerve (SON), the supratrochlear nerve (STN), and the maxillary nerve. Both reported improvements in their quality of life and ability to perform daily tasks during a 3-month follow-up period.

Conclusions: Short-term high cervical SCS at the C1–C2 spinal segments may be a feasible method to treat recent-onset V3 TPHN in elderly patients. Additionally, by placing the stimulation lead next to the external FR opening, we demonstrated a novel PNS approach to the maxillary nerve not previously reported for TPHN therapy.

Implantable Peripheral Nerve Stimulation for Trigeminal Neuropathic Pain: A Systematic Review and Meta-Analysis

OBJECTIVES

Implantable peripheral nerve stimulation has been increasingly used to treat neuropathic pain. This neuromodulation strategy may be an alternative option for intractable trigeminal neuropathic pain; however, evidence for this treatment approach remains limited. A systematic review was conducted to identify studies of patients that underwent peripheral nerve stimulation implantation for trigeminal neuropathic pain.

MATERIALS AND METHODS

Databases including, PubMed, EMBASE, and Cochrane Library were searched up to October 5, 2020. The primary outcomes were changes in pain scores and response rates of neuromodulation therapy. A random effects model was used for meta-analysis. Subgroup analysis was performed to examine the source of heterogeneity.

RESULTS

Thirteen studies including 221 participants were evaluated. The estimated response rate of neuromodulation treatment was 61.3% (95% CI: 44.4-75.9%, I²  = 70.733%, p < 0.0001) at the last follow-up. The overall reduction in pain scores was 2.363 (95% CI: 1.408-3.319, I²  = 85.723%, p < 0.0001). Subgroup analysis further confirmed that stimulation target (peripheral branch vs. trigeminal ganglion vs. trigeminal nerve root) contributed the heterogeneity across enrolled studies. Better clinical outcome was associated with stimulation of the trigeminal peripheral branch (p < 0.0001).

CONCLUSION

Peripheral nerve stimulation may be a promising approach in the management of trigeminal neuropathic pain, especially for patients intractable to conventional therapy.

Peripheral nerve field stimulation in medically refractory trigeminal neuralgia attributed to multiple sclerosis

OBJECTIVE

Case reports and small patient series have suggested peripheral nerve field stimulation (PNFS) as a treatment for refractory trigeminal neuralgia attributed to multiple sclerosis (MS). Here, the authors aimed to assess the effects of this technique on long-term pain severity.

METHODS

Data were prospectively collected on patients with refractory trigeminal neuralgia attributed to MS who underwent PNFS between July 2013 and August 2017 at the authors’ neurosurgical department. Patients were evaluated before and after the first treatment as well as at follow-up at least twice a year. Patients underwent assessment of their pain severity using the Barrow Neurological Institute (BNI) Scale before treatment and at follow-up and were questioned about adverse events following cranial MRI performed after implantation of a permanent PNFS system.

RESULTS

Eight patients (3 women) underwent PNFS trials and their median age was 61 years (IQR 73.75 − 46.5 years). Seven patients proceeded to permanent implantation of the stimulation system. At a median follow-up of 33 months (IQR 42 − 24 months), pain severity decreased from baseline to the last follow-up (BNI score decrease from V [IQR V − V] to III [IQR V − III], p = 0.054). Four patients experienced long-lasting benefit (at 48, 33, 24, and 15 months’ follow-up, respectively), while in 3 patients the treatment eventually failed after an initially successful period. One patient had an infection, requiring system removal and subsequent reimplantation. No other complications occurred. No adverse events were noted in the patients undergoing MRI postimplantation.

CONCLUSIONS

This analysis indicates a possibly beneficial long-term effect of PNFS on refractory trigeminal neuralgia attributed to MS in some patients.

Programming Parameters and Techniques in Trigeminal Ganglion Stimulation for Intractable Facial Pain

OBJECTIVES

Atypical facial pain syndromes are challenging disorders to manage and often incur limited benefit with surgery for classical trigeminal neuralgia presentations, such as microvascular decompression or ablative procedures. Neurostimulation of the trigeminal ganglion and peripheral nerves can be effective at treating atypical presentations of trigeminal facial pain affecting the V1-3 dermatomes, and the surgical techniques are well described. The stimulation parameters, however, have thus far received limited description; we therefore sought to describe programming strategies.

MATERIALS AND METHODS

We performed a retrospective chart review, examining patients that underwent trigeminal ganglion stimulation (TGS) and nerve branch stimulation for atypical facial pain and trigeminal neuropathic pain, and describe the programming strategies in detail.

RESULTS

We describe the use of high-frequency stimulation (1000 Hz), with alteration in pulse width (60-220 msec) and amplitude (0.5-3 V) to achieve effective treatment of refractory trigeminal facial pain. These parameters differ from existing published parameters for trigeminal nerve branch stimulation. We also describe the programming of specific contacts on each lead to target specific aspects of the individual patients' facial pain.

CONCLUSIONS

The use of effective programming strategies is critical to the success of neurostimulation surgical treatments; however, the critical details in programming strategies typically receive limited description. We report on the use of several successful programming strategies for TGS, to assist pain providers in successfully applying these surgical techniques in these difficult to manage atypical facial pain syndromes.

Craniofacial Peripheral Nerve Stimulation: Analysis of a Single Institution Series

OBJECTIVE

Objective real-world experience with peripheral nerve stimulation (PNS) is limited. Furthermore, the lack of robust outcome metrics, long-term follow-up and data comparing responders and nonresponders limit the refinement of selection criteria to better identify patients likely to benefit from PNS.

MATERIALS AND METHODS

We retrospectively analyzed 22 patients with craniofacial pain treated with PNS, and responders were classified as having ≥50% postoperative improvement in the numeric rating scale (NRS). In a subset of patients (n = 11), detailed prospective outcomes metrics were obtained preoperatively and postoperatively, including NRS, Beck Depression Index (BDI), Pain Catastrophizing Scale (PCS), and McGill Pain Questionnaire (MPQ).

RESULTS

About 59.1% (13 of 22) of subjects were classified as responders at a mean follow-up of 37.5 ± 5.27 months. Diagnoses included migraine (n = 6), occipital neuralgia (n = 9), trigeminal neuropathic pain (TNP; n = 6), and central poststroke pain (n = 1). Within the TNP subgroup, responders were more likely to have undergone two or more trigeminal neuralgia procedures prior to PNS (p < 0.05). In the 11 patients with comprehensive preoperative and postoperative outcome data, we noted significant improvement in NRS (p = 0.0005), BDI (p = 0.04), PCS (p = 0.01), as well as components of PCS (helplessness and magnification, p = 0.02) and MPQ (affective, p = 0.02).

CONCLUSIONS

The present study adds to the PNS literature by providing long-term data and multiple outcome metrics in a subset of patients. We suggest that BDI, PCS, and MPQ may provide more insight into meaningful response over time. Evaluating functional and quality of life outcomes in patients with craniofacial pain may be more informative than assessing benefit solely based on pain intensity and responder rates.

Placement and Anchoring of Trigeminal Neurostimulation Electrodes: Technical Report

BACKGROUND

Peripheral neurostimulation (PNS) for medically refractory trigeminal and craniofacial pain is an emerging alternative to traditional surgical approaches. Technical problems with craniofacial PNS have included electrode migration and erosion, limiting the utility and cost-effectiveness of this procedure.

OBJECTIVE

To review our institutional surgical technique for trigeminal PNS implantation, focusing on a novel technique for electrode anchoring.

METHODS

Consecutive cases of permanent craniofacial PNS placement by a single surgeon over 36 months were reviewed for surgical technique and technical outcomes. Electrodes were placed percutaneously with open anchoring to the pericranium at a separate parietal incision.

RESULTS

Sixteen systems (53 electrodes) were implanted in 14 patients. Median follow-up was 13 months (range, 5-29 months). Electrode placement was successful in all cases with no intraoperative complications. There was 1 lead migration (6.3% per patient; 1.8% per lead) and no cases of erosion. Two patients (14.3%) required explant for infection, 1 of whom was successfully reimplanted. Three patients (21.4%) underwent surgical revision other than for infection.

CONCLUSIONS

We present an improved method for craniofacial PNS surgery which introduces a separate incision for electrode anchoring at the parietal boss. This technique simplifies the procedure and greatly reduces rates of erosion and migration, improving patient comfort and satisfaction.

Evolving Techniques and Indications in Peripheral Nerve Stimulation for Pain

Peripheral nerve stimulation is the direct electrical stimulation of named nerves outside the central neuraxis to alleviate pain in the distribution of the targeted peripheral nerve. These treatments have shown efficacy in treating a variety of neuropathic, musculoskeletal, and visceral refractory pain pathologies; although not first line, these therapies are an important part of the treatment repertoire for chronic pain. With careful patient selection and judicious choice of stimulation technique, excellent results can be achieved for a variety of pain etiologies and distributions. This article reviews current and past practices of peripheral nerve stimulation and upcoming advancements in the field.

Double Blinded Randomized Trial of Subcutaneous Trigeminal Nerve Stimulation as Adjuvant Treatment for Major Unipolar Depressive Disorder

BACKGROUND

More than 30% of major depressive disorder patients fail to respond to adequate trials of medications and psychotherapy. While modern neuromodulation approaches (ie, vagal nerve stimulation, deep brain stimulation) are yet to prove their efficacy for such cases in large randomized controlled trials, trigeminal nerve stimulation (TNS) has emerged as an alternative with promising effects on mood disorders.

OBJECTIVE

To assess efficacy, safety, tolerability, and placebo effect duration of continuous subcutaneous TNS (sTNS) in treatment-resistant depression (TRD).

METHODS

The TREND study is a single-center, double-blind, randomized, controlled, phase II clinical trial. Twenty unipolar TRD patients will receive V1 sTNS as adjuvant to medical therapy and randomized to active vs sham stimulation throughout a 24-wk period. An additional 24-wk open-label phase will follow. Data concerning efficacy, placebo response, relapse, and side effects related to surgery or electrical stimulation will be recorded. We will use the HDRS-17, BDI-SR, IDS_SR30, and UKU scales.

EXPECTED OUTCOMES

The main outcome measure is improvement in depression scores using HAM-17 under continuous sTNS as adjuvant to antidepressants. Active stimulation is expected to significantly impact response and remission rates. Minor side effects are expected due to the surgical procedure and electrical stimulation. The open-label phase should further confirm efficacy and tolerability.

DISCUSSION

This study protocol is designed to define efficacy of a novel adjuvant therapy for TRD. We must strive to develop safe, reproducible, predictable, and well-tolerated neuromodulation approaches for TRD patients impaired to manage their lives and contribute with society.

Tibial nerve stimulation with a miniature, wireless stimulator in chronic peripheral neuropathic pain

Peripheral neuropathic pain (PNP) and complex regional pain syndrome (CRPS) can be effectively treated with peripheral nerve stimulation. In this clinical trial report, effectiveness of novel, miniature, wirelessly controlled microstimulator of tibial nerve in PNP and CRPS was evaluated. In this pilot study the average preoperative visual analog scale (VAS) score in six patients was 7.5, with 1, 3 and 6 months: 2.6 (p=0.03), 1.6 (p=0.03), and 1.3 (p=0.02), respectively. The mean average score in the six patients a week preceding the baseline visit was 7.96, preceding the 1, 3 and 6 month visits: 3.32 (p=0.043), 3.65 (p=0.045), and 2.49 (p=0.002), respectively. The average short-form McGill pain score before surgery was 23.8, and after 1, 3 and 6 months it was 11.0 (p=0.45), 6.3 (p=0.043), and 4.5 (p=0.01), respectively. Applied therapy caused a reduction of pain immediately after its application and clinical improvement was sustained on a similar level in all patients for six months. No complications of the treatment were observed. Intermittent tibial nerve stimulation by using a novel, miniature, wirelessly controlled device can be effective and feasible in PNP and CRPS. It is a safe, minimally invasive, and convenient neuromodulative method.

Peripheral neuromodulation for the treatment of refractory trigeminal neuralgia

Trigeminal neuralgia is an extremely painful condition. Treatment options for trigeminal neuralgia include anticonvulsants, opioids and surgical methods; however, some cases may be refractory to these therapies. In this article, the authors report a case involving a patient for whom conventional treatments failed; she underwent a successful trial of peripheral nerve stimulation and subsequently opted for a permanent implantation of an internal pulse generator, leading to long-term relief of her pain.

Trigeminal neuralgia is a type of orofacial pain that is diagnosed in 150,000 individuals each year, with an incidence of 12.6 per 100,000 person-years and a prevalence of 155 cases per 1,000,000 in the United States. Trigeminal neuralgia pain is characterized by sudden, severe, brief, stabbing or lancinating, recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve, which can cause significant suffering for the affected patient population.

In many patients, a combination of medication and interventional treatments can be therapeutic, but is not always successful. Peripheral nerve stimulation has gained popularity as a simple and effective neuromodulation technique for the treatment of many pain conditions, including chronic headache disorders. Specifically in trigeminal neuralgia, neurostimulation of the supraorbital and infraorbital nerves may serve to provide relief of neuropathic pain by targeting the distal nerves that supply sensation to the areas of the face where the pain attacks occur, producing a field of paresthesia within the peripheral distribution of pain through the creation of an electric field in the vicinity of the leads.

The purpose of the present case report is to introduce a new, less-invasive interventional technique, and to describe the authors’ first experience with supraorbital and infraorbital neurostimulation therapy for the treatment of trigeminal neuralgia in a patient who had failed previous conservative management.

Peripheral nerve field stimulation for trigeminal neuralgia, trigeminal neuropathic pain, and persistent idiopathic facial pain

Objective

Peripheral nerve field stimulation (PNFS) is a promising modality for treatment of intractable facial pain. However, evidence is sparse. We are therefore presenting our experience with this technique in a small patient cohort.

Methods

Records of 10 patients (five men, five women) with intractable facial pain who underwent implantation of one or several subcutaneous electrodes for trigeminal nerve field stimulation were retrospectively analyzed. Patients’ data, including pain location, etiology, duration, previous treatments, long-term effects and complications, were evaluated.

Results

Four patients suffered from recurrent classical trigeminal neuralgia, one had classical trigeminal neuralgia and was medically unfit for microvascular decompression. Two patients suffered from trigeminal neuropathy attributed to multiple sclerosis, one from post-herpetic neuropathy, one from trigeminal neuropathy following radiation therapy and one from persistent idiopathic facial pain. Average patient age was 74.2 years (range 57–87), and average symptom duration was 10.6 years (range 2–17). Eight patients proceeded to implantation after successful trial. Average follow-up after implantation was 11.3 months (range 5–28). Using the visual analog scale, average pain intensity was 9.3 (range 7–10) preoperatively and 0.75 (range 0–3) postoperatively. Six patients reported absence of pain with stimulation; two had only slight constant pain without attacks.

Conclusion

PNFS may be an effective treatment for refractory facial pain and yields high patient satisfaction.

Trigeminal branch stimulation for the treatment of intractable craniofacial pain

OBJECT

Trigeminal branch stimulation has been used in the treatment of craniofacial pain syndromes. The risks and benefits of such an approach have not been clearly delineated in large studies, however. The authors report their experience in treating craniofacial pain with trigeminal branch stimulation and share the lessons they have learned after 93 consecutive electrode placements.

METHODS

A retrospective review of all patients who underwent trigeminal branch electrode placement by the senior author (C.J.W.) for the treatment of craniofacial pain was performed.

RESULTS

Thirty-five patients underwent implantation of a total of 93 trial and permanent electrodes between 2006 and 2013. Fifteen patients who experienced improved pain control after trial stimulation underwent implantation of permanent stimulators and were followed for an average of 15 months. At last follow-up 73% of patients had improvement in pain control, whereas only 27% of patients had no pain improvement. No serious complications were seen during the course of this study.

CONCLUSIONS

Trigeminal branch stimulation is a safe and effective treatment for a subset of patients with intractable craniofacial pain.

The appropriate use of neurostimulation: stimulation of the intracranial and extracranial space and head for chronic pain. Neuromodulation Appropriateness Consensus Committee

INTRODUCTION

The International Neuromodulation Society (INS) has identified a need for evaluation and analysis of the practice of neurostimulation of the brain and extracranial nerves of the head to treat chronic pain.

METHODS

The INS board of directors chose an expert panel, the Neuromodulation Appropriateness Consensus Committee (NACC), to evaluate the peer-reviewed literature, current research, and clinical experience and to give guidance for the appropriate use of these methods. The literature searches involved key word searches in PubMed, EMBASE, and Google Scholar dated 1970-2013, which were graded and evaluated by the authors.

RESULTS

The NACC found that evidence supports extracranial stimulation for facial pain, migraine, and scalp pain but is limited for intracranial neuromodulation. High cervical spinal cord stimulation is an evolving option for facial pain. Intracranial neurostimulation may be an excellent option to treat diseases of the nervous system, such as tremor and Parkinson's disease, and in the future, potentially Alzheimer's disease and traumatic brain injury, but current use of intracranial stimulation for pain should be seen as investigational.

CONCLUSIONS

The NACC concludes that extracranial nerve stimulation should be considered in the algorithmic treatment of migraine and other disorders of the head. We should strive to perfect targets outside the cranium when treating pain, if at all possible.

Novel High-Frequency Peripheral Nerve Stimulator Treatment of Refractory Postherpetic Neuralgia: A Brief Technical Note

OBJECTIVES

The study aims to describe an ultrasound (US)-guided peripheral nerve stimulation implant technique and describe the effect of high-frequency peripheral nerve stimulation on refractory postherpetic neuralgia.

MATERIALS AND METHODS

Following a cadaver pilot trial using US and confirmatory fluoroscopic guidance, a 52-year-old man with refractory left supraorbital neuralgia underwent combined US and fluoroscopic-guided supraorbital peripheral nerve stimulator trial. The patient was subsequently implanted with a percutaneous lead over the left supraorbital and supratrochlear nerve utilizing a high-frequency stimulation paradigm.

RESULTS

At 9 months follow-up, the pain intensity had declined from a weekly average of 8/10 to 1/10 on the pain visual analog scale (VAS). After implant, both nerve conduction and blink reflex studies were performed, which demonstrated herpetic nerve damage and frequency-specific peripheral nerve stimulation effects. The patient preferred analgesia in the supraorbital nerve distribution accomplished with high-frequency paresthesia-free stimulation (HFS) at an amplitude of 6.2 mA, a frequency of 100-1200 Hz, and a pulse width of 130 μsec, to paresthesia-mediated pain relief associated with low-frequency stimulation.

CONCLUSION

We report the implant of a supraorbital peripheral nerve stimulating electrode that utilizes a high-frequency program resulting in sustained suppression of intractable postherpetic neuralgia.

Technological innovations in implants used for pain therapies

The field of pain management has experienced tremendous growth in implantable therapies secondary to the innovations of bioengineers, implanters, and industry. Every aspect of neuromodulation is amenable to innovation from implanting devices to anchors, electrodes, programming, and even patient programmers. Patients with previously refractory neuropathic pain syndromes have new and effective pain management strategies that are a direct result of innovations in implantable devices.

Supraorbital and supratrochlear stimulation for trigeminal autonomic cephalalgias

Trigeminal autonomic cephalalgias (TAC) is a rare primary headache disorder with challenging and limited treatment options for those unfortunate patients with severe and refractory pain. This article will review the conventional pharmacologic treatments as well as the new neuromodulation techniques designed to offer alternative and less invasive treatments. These techniques have evolved from the treatment of migraine headache, a much more common headache syndrome, and expanded towards application in patients with TAC. Specifically, the article will discuss the targeting of the supratrochlear and supraorbital nerves, both terminal branches of the trigeminal nerve.

A systematic review: current and future directions of dorsal root ganglion therapeutics to treat chronic pain

OBJECTIVE

The purpose of the study was to systematically review the historical therapeutics for chronic pain care directed at the dorsal root ganglion (DRG) and to identify future trends and upcoming treatment strategies.

METHODS

A literature search on bibliographic resources, including EMBASE, PubMed Cochrane Database of Systemic Reviews from literature published from 1966 to December 1, 2012 to identify studies and treatments directed at the DRG to treat chronic pain, and was limited to the English language. Case series, case reports, and preclinical work were excluded. Information on emerging technologies and pharmacologics were captured separately, as they did not meet the inclusion criteria.

RESULTS

The literature review yielded three current clinical treatment strategies: ganglionectomy, conventional radiofrequency treatment of the dorsal root ganglion, and pulsed radiofrequency treatment of the DRG. Seven studies were identified utilizing ganglionectomy, 14 for conventional radiofrequency, and 16 for pulsed radiofrequency. Electrical stimulation and novel therapeutic delivery strategies have been proposed and are in development.

CONCLUSIONS

Despite a robust understanding of the DRG and its importance in acute nociception, as well as the development and maintenance of chronic pain, relatively poor evidence exists regarding current therapeutic strategies. Novel therapies like electrical and pharmacologic strategies are on the horizon, and more prospective study is required to better qualify the role of the DRG in chronic pain care.

Peripheral nerve stimulation in treatment of intractable postherpetic neuralgia

Objective.  This case report presents an application of peripheral nerve stimulation to a patient with intractable postherpetic neuralgia that conventional treatment failed to ameliorate. Methods.  The patient underwent an uneventful peripheral nerve stimulator trial with placement of two temporal eight-electrode percutaneous leads (Octrode leads, Advanced Neuromodulation Systems, Plano, TX, USA) into the right subscapular and right paraspinal area of the upper thoracic region. Results.  Upon experiencing excellent pain relief over the next two weeks, the patient underwent implantation of permanent leads two weeks later and reported sustained pain relief. Conclusion. Peripheral nerve stimulation offers an alternative treatment option for intractable pain associated with postherpetic neuralgia, especially for elderly patients where treatment options are limited due to existing comorbidities. Further studies are warranted.

Case report: successful epiradicular peripheral nerve stimulation of the C2 dorsal root ganglion for postherpetic neuralgia

BACKGROUND

Postherpetic neuralgia (PHN) is the most common complication following an acute varicella zoster virus infection. PHN often results in a chronic severe pain condition refractory to conservative pain management treatments. Peripheral nerve stimulation over the affected spinal nerve root may be an effective treatment option for patients with intractable PHN.

OBJECTIVE

To describe a successful case of peripheral nerve stimulation of the second cervical dorsal root ganglion for the treatment of intractable PHN.

CASE REPORT

An 80-year-old man with a 15-month history of severe PHN was referred to our clinic for pain management. His pain was localized to the left side in the distribution of the C2 dermatome. The patient's pain was unresponsive to comprehensive conventional treatments for PHN including physical therapy, membrane stabilizing medications, opioids, anti-inflammatories, cervical epidural steroid injections, cervical facet joint injections, and dorsal root ganglion blockade with pulsed radiofrequency. After failing to respond to conservative and interventional therapies, a peripheral nerve stimulator trial was conducted for a period of seven days. The lead was placed within the epidural space over the atlanto-axial joint under fluoroscopy to stimulate the left C2 nerve root. This trial resulted in a significant decrease of the patient's pain, and discontinuation of all pain medications.

CONCLUSION

We describe a case of successful electrode placement at the C2 spinal level for the treatment of refractory PHN.

Repositioning of supraorbital nerve stimulation electrode using retrograde needle insertion: a technical note

INTRODUCTION

With growing interest and acceptance of peripheral nerve stimulation (PNS) approach, there is now an increasing need in developing clear procedural details to resolve frequent complications and minimize associated tissue injury. Migration and suboptimal positioning of PNS electrodes are one of the most commonly observed complications of PNS approach.

MATERIALS AND METHODS

We present a simple technique for repositioning a supraorbital electrode using retrograde insertion of introducer needle that allows one to place percutaneous (cylindrical) PNS electrode into appropriate anatomical location with minimal additional injury to surrounding tissues.

RESULTS

This approach has been successfully used in multiple cases. An illustrative case of electrode revision with proposed technique is described in detail.

CONCLUSION

This technically simple approach to repositioning of cylindrical supraorbital electrodes using retrograde needle insertion eliminates the need for a more elaborate and invasive procedure. The technique can be used for electrode repositioning in most PNS applications.

Prospective clinical study of a new implantable peripheral nerve stimulation device to treat chronic pain

OBJECTIVES

To evaluate clinical use of the StimRouter, an investigational implanted peripheral nerve stimulator for treating chronic neuropathic pain, using the median nerve as a model for that general application.

METHODS

Eight patients with carpal tunnel syndrome and chronic pain despite both carpal tunnel release and treatment with oral pain medications were enrolled in a single-center, open-label trial after institutional review board approval. Primary endpoints were successful implantation near the target peripheral nerve and safety. All 8 patients were implanted temporarily at the median nerve in at least one arm and 2 patients were implanted bilaterally, with 10 implants total. Each implant was considered a separate "patient." For 5 days, all patients received 6 hours of daily transdermal electrical stimulation targeting the median nerve. Pain was measured at baseline, during implant, and after explant.

RESULTS

Two patients experienced clinically meaningful (>or=30%) pain reduction throughout the entire 5-day treatment period. Apparent carryover effect in pain reduction also was observed after daily stimulation. After explant, pain returned to baseline, increasing 36.8% to 45.6% relative to average reduced pain with daily stimulation. No significant or unexpected adverse events occurred. Mean patient study satisfaction was 96%, and 100% of patients indicated a preference for permanent implant.

DISCUSSION

Temporary implant of the StimRouter device resulted in both pain reduction and reduced use of oral opioid pain medication during the 5-day stimulation period. The results suggest that permanent implant of the StimRouter System may be safe and effective for treating chronic peripheral neuropathic pain.

Successful treatment of an intractable postherpetic neuralgia (PHN) using peripheral nerve field stimulation (PNFS)

Postherpetic neuralgia (PHN) is a chronic neuropathic pain syndrome that arises as a sequel of herpes zoaster eruption. The treatment of postherpetic neuralgia is medically challenging and often frustrating in some situation as the exact mechanism of neuralgia is poorly understood and multiple and complex pathophysiology is postulated requiring poly pharmacy, which itself leads to many side effects. Here, we present a successful management of supra-orbital PHN using peripheral nerve field stimulation (PNFS), which was refractory to the commonly used pharmacological treatment. After successful trial stimulation, permanent stimulator was placed successfully, patient medication were tapered off within 2 weeks. At present, patient is in 8-week poststimulation with excellent pain relief, without any side effect.

Peripheral subcutaneous stimulation for the treatment of intractable postherpetic neuralgia: two case reports and literature review

Postherpetic neuralgia (PHN) is a common cause of chronic pain in the elderly. Antidepressants, anticonvulsants, and opioids may reduce discomfort in many patients, while others have pain intractable to all forms of therapy. We present a novel treatment approach for intractable PHN utilizing percutaneous peripheral nerve stimulation. Two cases are described in which an 80-year-old man and a 67-year-old woman with intractable PHN, lasting 2 and 10 years, respectively, were effectively treated with implantation of two octapolar leads in the lateral thoracic region. These cases suggest that peripheral nerve stimulation may offer an alternative treatment option for intractable pain associated with PHN especially in the elderly where treatment options are limited because of existing comorbidities.

Peripheral nerve stimulation for neuropathic pain

Peripheral nerve stimulation (PNS) has been used for treatment of neuropathic pain for more than 40 years. Recent resurgence of interest to this elegant surgical modality came from the introduction of less invasive implantation techniques and the wider acceptance of neuromodulation as a treatment of medically refractory cases. This article reviews the literature on the use of PNS for neuropathic pain and describes current indications and hardware choices in frequent use. Published experience indicates that neuropathic pain responds to PNS in many patients. PNS works well in both established indications, such as post-traumatic and postsurgical neuropathy, occipital neuralgia, and complex regional pain syndromes, and in relatively new indications for neuromodulation, such as migraines and daily headaches, cluster headaches, and fibromyalgia. Future research and growing clinical experience will help in identifying the best candidates for PNS, choosing the best procedure and best hardware for each individual patient, and defining adequate expectations for patients and pain specialists.

Current algorithm for the surgical treatment of facial pain

BACKGROUND

Facial pain may be divided into several distinct categories, each requiring a specific treatment approach. In some cases, however, such categorization is difficult and treatment is ineffective. We reviewed our extensive clinical experience and designed an algorithmic approach to the treatment of medically intractable facial pain that can be treated through surgical intervention.

METHODS

Our treatment algorithm is based on taking into account underlying pathological processes, the anatomical distribution of pain, pain characteristics, the patient's age and medical condition, associated medical problems, the history of previous surgical interventions, and, in some cases, the results of psychological evaluation. The treatment modalities involved in this algorithm include diagnostic blocks, peripheral denervation procedures, craniotomy for microvascular decompression of cranial nerves, percutaneous rhizotomies using radiofrequency ablation, glycerol injection, balloon compression, peripheral nerve stimulation procedures, stereotactic radiosurgery, percutaneous trigeminal tractotomy, and motor cortex stimulation. We recommend that some patients not receive surgery at all, but rather be referred for other medical or psychological treatment.

RESULTS

Our algorithmic approach was used in more than 100 consecutive patients with medically intractable facial pain. Clinical evaluations and diagnostic workups were followed in each case by the systematic choice of the appropriate intervention. The algorithm has proved easy to follow, and the recommendations include the identification of the optimal surgery for each patient with other options reserved for failures or recurrences. Our overall success rate in eliminating facial pain presently reaches 96%, which is higher than that observed in most clinical series reported to date

CONCLUSION

This treatment algorithm for the intractable facial pain appears to be effective for patients with a wide variety of painful conditions and may be recommended for use in other institutions.

Supraorbital Nerve Electric Stimulation for the Treatment of Intractable Chronic Cluster Headache: A Case Report

We describe a patient with intractable chronic cluster headache that responded well to supraorbital nerve electric stimulation.